How the scheduling engine reaches a result

Each template is an immutable ID and version with an exact cycle matrix, crew count, shift IDs, default local times, and source notes. The selector, schedule engine, pattern pages, and tests all consume that same registry.

For each inclusive calendar date, the engine finds the positive day offset from the cycle anchor, resolves that position in each crew phase, and converts the selected local shift endpoints into real instants in the chosen IANA time zone.

Every visible view and export consumes the same effective assignments after manual overrides. Readiness fails closed: a blocker produces Draft, prevents ICS export, remains in the shared snapshot summary, and appears as a print watermark.

• Blockers: missing or repeated coverage, invalid local times, unknown template versions, overlapping crew or member assignments, and real gaps or overlaps between required shift definitions.
• Planning warnings: empty crews, member-count targets, short rest intervals, and elapsed shift duration changes across daylight-saving transitions.
• Information: a local time was ambiguous during a clock change and the documented earlier instant was selected.

The checks only evaluate the information in the document. They do not know actual attendance, skills, qualifications, leave, bargaining agreements, jurisdiction-specific rules, travel, handoff duties, or individual fitness for duty.

OSHA and NIOSH describe fatigue as a workplace risk associated with long, irregular, night, and nonstandard schedules. These references explain why a planning warning is not a medical or legal conclusion and why responsible teams must perform their own review.